Conventional fixing devices for performing a fixing treatment for a sheet include a pair of rotary members each rotatable around a rotation shaft. A sheet passes through a nip defined between the pair of rotary members, whereby a developer image on the sheet is fixed. In such a fixing device, the rotary member is rotatably and axially supported by a specific bearing.
Japanese Unexamined Patent Publication No. 2004-77678 discloses a technique of placing a conical spring washer in respective spaces between the opposite end surfaces of a rotary member and corresponding bearings in order to fix the bearings and a driving gear at respective predetermined retaining positions. Each of the conical spring washers exerts a biasing force to thereby prevent the bearing and the driving gear from axially shifting with respect to each other.